Personally, I've not found an editor which has a live editing diff view where new lines are highlighted green and deleted lines are still visible but highlighted red which I think would be useful.
I often use different editors (and on different computers), so keyboard shortcuts may differ. Sometimes I can't remember the shortcut for what I want to do, so it would be very handy to press F1 and see a little cheatsheet of all the available shortcuts, instead of opening the settings menu and clicking through 4-5 submenus to find it.
Other than that I'm quite happy with todays editors. I'm coding in both Windows and Linux environments and all my editors works great for both.
For larger projects I use Netbeans 8.2 (Web backend and frontend). It comes with everything I need out of the box, the only plugin I sometimes use is the Zend HTML thingy (for creating HTML markup macros).
For Python projects I use Jetbrain Pycharm.
For anything else where I don't really need advanced features like PHPdoc or autocomplete I tend to open Atom (previously Sublime Text until the Atom hype got me).
The editor should install shortcuts to often-used-code patterns of a package that you just installed.
In webstorm - on typing 'descnew' I get like 12-15 lines of boiler plate [0] (descnew = describe new test group - have a live template setup in webstorm). I am sure many use feature like this - but wouldn't that be cool if it comes packaged and are universal between editors.
an as you type highlighting spelling checker - hopefully that would distinguish between code and text/comment blocks.
an FTP manager.